The overall goal of our research this coming year will be to further evaluate the regulation of T-cell function in delayed hypersensitivity, antibody formation and in vitro blastogenesis. These experiments are an outgrowth of our work on the cellular aspects of acquired immunologic tolerance and are directed toward determining whether or not the same subset of T-cells is involved in in vivo delayed hypersensitivity antibody formation and in vitro blastogenesis. These goals are being approached experimentally by determining the capacity of lymph node and splenic T-cells to mediate T-helper function, in vivo delayed hypersensitivity and in vitro blastogenesis to sheep erythrocytes and human-gamma-globulin under a variety of regulatory situations known to effect one of the three functions. We are particularly concerned with the ability of suppressor cells and/or antigen-specific suppressor factors from tolerant or primed mice to regulate the above T-cell functions.. The homing capability of the suppressor cells involved in inhibiting the above responses will be evaluated by considering the responses of at least two separate organs, spleen and lymph nodes, and the distribution of suppressor cells in these organs. Lastly, antisera to Ly 2 and Ly 1 will be used to differentiate between excess helper cells (TH) and suppressor cells (TS) as the inhibitor of delayed hypersensitivity during an antibody response.